Cow flatulence is kind of funny, but it's no joke. Bovine belching and farting are pretty significant sources of methane gas, which makes them not insignificant contributors of the greenhouse gases behind global climate change. Methane is also the main ingredient in natural gas, and as anyone who has watched Mad Max Beyond Thunderdome knows, livestock-produced methane can (in theory) be harnessed to produce large amounts of electricity.Last fall, Argentina turned that theory into practice. The country's National Institute of Agricultural Technology (INTA) came up with a method of capturing cow-produced methane before it enters the atmosphere through the mouth or intestinal tract, then compressing that gas and using it to make biofuel to generate electricity or even power a car. "A cow emits about 300 liters of methane a day," or 80 gallons, explains INTA technician Ricardo Buelo.Basically, INTA's contraption starts with a tube inserted through a cow's skin and into the rumen, or the largest of a cow's digestive tracts. The other end of the tube is connected to a backpack that collects the gas, which is then condensed down into usable form. INTA insists that the procedure is painless for the cow.